#define _CRT_SECURE_NO_WARNINGS 1
#include <stdio.h>
int max(int a, int b, int c)
{
    int max = a;
    max > b ?max : (max = b);
    max > c ?max : (max = c);
    return max;
}

int main() {
    float m = 0;
    int a, b, c;
    scanf("%d %d %d", &a, &b, &c);
    max(a, b, c);
    m = (1.0 * max(a + b, b, c)) / (max(a, b + c, c) + max(a, b, b + c));
    printf("%.2f", m);
    return 0;
}